Sparks in the microwave — without metal! (Don’t try this at home)
I was using my microwave to thaw some frozen chopped green peppers in a small Pyrex dish (not much, just enough to top a couple of Italian sausages on buns along with tomato and onion), and to my surprise, there was an electric arc within the dish, even though there was no metal within. I wondered how this might happen, so I did some Googling, and I came upon this page that explains the physics:
That’s about grapes sparking in the microwave, but the principles seem about the same — small objects close in size to the microwaves’ wavelength, with small gaps between them filled with steam as the water inside evaporates. The pepper pieces were rectangular instead of round, but then, grapes aren’t perfect spheres anyway, so the model presented there is just an approximation.
And I’ll repeat what the link says — this is not something you want to try at home, since you could damage your microwave. Luckily I caught it and hit the stop button within a second. But in the future, I should consider finding another way to thaw my green peppers — or maybe just start buying them fresh (although I don’t know if I use them often enough for that — how well do they keep?).